Turbocompounding Application for Small Displacement Engines

In order to reduce greenhouse gases and respect stringent pollutant emission regulations, energy recovery of internal combustion engines is of primary interest to increase engine global efficiency. Exhaust energy is one of the most promising solutions due to its high availability comparing to other engine losses. In this context, this paper deals with exhaust energy recovery by turbocompounding focusing on a passenger car application.
Turbocompounding is already established in heavy-duty engines, in which an additional stage of expansion is made through an exhaust recovery turbine. However, the engine working conditions are far different for passenger car ones.
In this context, this paper deals with a simulation study of turbobocompound, applied to a small displacement Diesel engine. The turbocompounded engine is compared to the baseline engine by maintaining constant the mass of fuel injected during the engine cycle. A global steady-state study over the entire engine map is discussed.
The turbocompound interactions with the engine reveals by affecting different parameters as the pumping loop, the boosting effect, the scavenging and all the engine thermodynamic balance.
The potential of the system is evaluated by the global gain represented by the exhaust recovered power subtracted by the engine lost power due to back pressure.
Finally, conclusions are drawn on the practicality of installing such system on a small displacement engine.